public String extractMultiples(String plainString, String targeted) {
StringBuffer sb = new StringBuffer();
// split covers all occurrences in the beginning;empty element, and in
// the middle
String[] result = plainString.split(targeted);
for (int i = 0; i < result.length; i++) {
sb.append(result[i]);
if (i < result.length - 1)// not the last one
sb.append(targeted);
}
// in the end
if (plainString.endsWith(targeted))
sb.append(targeted);
return sb.toString();
}